Research

In tropical rainforests, much of the plant world unfolds high above the ground. Orchids, bromeliads and many ferns grow on branches and tree trunks rather than in the soil. These so-called epiphytes – plants that grow on other plants – make up almost 10 percent of all vascular plant species worldwide. The advantages of this unusual lifestyle are obvious: in the forest canopy plants can reach more light and do not need to invest energy in building a massive trunk like trees do. But life high above the ground also comes with challenges. Without roots in the soil, obtaining water and nutrients can be difficult. Despite these constraints, this lifestyle has evolved in several plant families. At the same time, close relatives of many epiphytes still grow on the forest floor and often look remarkably similar. Why does one species live exclusively on trees while its relatives remain rooted in the ground? An international research project led by the Institute of Botany at BOKU University in Vienna is now investigating a little-tested explanation: plants may have moved into the tree canopy to escape their enemies in the soil. Particularly dangerous are pathogenic fungi that attack seeds and young seedlings. This idea is known as the “Epiphyte Enemy Escape” hypothesis. Over the course of evolution, plants develop genetic defenses against such pathogens. But if a species no longer encounters certain pathogens for multiple generations, these defenses may be lost – following the evolutionary principle of “use it or lose it.” Epiphytes might therefore become highly susceptible to soil pathogens and be unable to survive on the forest floor. The FWF-funded project “EpiEneScape” will test this hypothesis using simple but revealing experiments. Researchers will germinate seeds of epiphytic species and their ground-dwelling relatives on different substrates – such as forest soil and materials from tree branches. This will show where young plants are able to grow successfully and where they fail. In addition, the team will measure functional traits such as water storage capacity to better understand how these plants are adapted to the very different conditions in the canopy and on the forest floor. The study is a collaboration between BOKU University Vienna and the Universidad Veracruzana in Mexico. Fieldwork and experiments will take place both in greenhouses and in the tropical lowland and montane rainforests of Mexico. The researchers hope their findings will help explain why so many plant species have evolved to live in the forest canopy – and what role natural enemies in the soil may have played in shaping this remarkable lifestyle.

Forests, especially structurally rich deciduous forests with old trees, are essential habitats for most native bat species. They serve as hunting grounds as well as summer and winter quarters. In Lower Austria, especially in the Weinviertel, there are such forests that have a high density of endangered species such as the Alcathoe bat, Bechstein's bat and Geoffroy's bat. However, intensive agriculture is fragmenting these habitats, threatening the genetic diversity and stability of bat populations. The project “From Isolation to Connectivity: Bats in Fragmented Forests” aims to promote habitat connectivity. In the Großweikersdorf model region, crucial structures are identified that ensure the connection between summer and winter quarters. Using telemetry, genetic analysis and connectivity analysis, movement patterns and networking structures are examined. Public relations work is intended to increase awareness of the need to protect bats and their habitats. The results of the project are intended to provide model solutions for other regions and contribute to the conservation of bat biodiversity.

Anthropogenic destruction of biosphere integrity is rapidly progressing. It even affects remote high mountain regions, questioning their role as biodiversity refuges in times of climate change. Although cold-determined alpine ecosystems are globally distributed, they are often very small-scale and fragmented, so that their disproportionally rich and unique vascular plant diversity is highly threatened through impacts of rising temperatures. This project will use the international GLORIA (https://gloria.ac.at) data set to understand changes in alpine plant diversity in summit zones that have been observed globally since the beginning of this century. By a worldwide compilation of standardised alpine vegetation data and integration of data on ecological drivers, the planned analyses deal with three main hypotheses: (1) changes in species numbers and composition are related to regional velocities of climate change, (2) combinations of reduced cold stress and increased drought stress accelerates loss of alpine plant diversity and (3) small-ranged species are overrepresented among declining and widespread ones among the gaining plants, being particularly worrisome in isolated small-scale alpine regions. We will use (1) data from repeated recordings of permanent plots, distributed over 100 alpine regions of the main mountain systems on Earth, combined with (2) remote sensing data of topography, changes in vegetation greenness and snow cover, (3) in situ-measured soil temperature and gridded climate data series as well as (4) data of species’ overall distribution and their thermic and hydrological niches in order to analyse and assess the magnitude and rates of biodiversity changes in relation to the main drivers.